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MC4 connectors a massive scandal

Boron

Solar Enthusiast
Joined
Oct 26, 2023
Messages
368
Location
UK
High Solarnerds, have you had bad experiences with MC4 connectors?
I got some recently from Alix - yes dont all jump on me here. It was for the purpose of examining what fake products were like (not for serious use OK).
Looking closely at the basic design, its been carefully formulated originally by authorities (Google it yourself, its way too much for discussion here). Suffice to say that what started out as well intended has IMHO turned out to be a monumental dog's breakfast with serious fire risks associated. This is common knowledge within the installer/ cowboy experts. Unfortunately, for what they are, the original devices are quite expensive ca £5 a pair , whereas the fake products (look identical) are 1/10th of that price. How would a naive customer know the difference. There are many YT vids showing how fires occur with faulty connections - and worse still on a roof where a fault may persist undetected for some time till it results in a dramatic sustained arc/fire one sunnny day and the potential to burn your house down. Some of these connectors maybe hidden and inaccessible beneath roof tiles for example.
In short - there are many manufacturer's in this lucrative trough with only a few who have a credible quality product (I defer to this boards proper rules and do attempt any commercial promotions, however there is a Wiki on the origins of the design https://en.wikipedia.org/wiki/MC4_connector.

My immediate experience resulted in my OP here as I was shocked to learned from an electricians vid about the installations industries dirty secret.
Ignore the first part on how to make an MC4 connection, goto 12:00 where he discusses the issue of connecting all the system components together (also ignore the commercial plug but it pays for an informed opinion IMHO).

In short, dont mix male/female parts from different manufacturers. The vids suggest there may be an ad hoc compatibility chart produced by some brands but will it help you on site?
When connecting your system makers usually present their equipment with a tail and a ready made MC4 connection. Some provide the mating other half for you to use on your own cable (but not always). So you may be faced with cutting off the kit suppliers connector and using a matching MC4 pair. This may invalidate the Kit suppliers warranty - a nasty grey area that should be challenged before buying your kit (eg Solar panels) - ie insist on a full MC4 coupling and preferably the full spec/maker etc in case a spare is needed . If MC4s give trouble they should be immediately cut out and replaced - not just quick fix , uncoupled and refit a few times hoping that will solve the problem - it will almost certainly return. Up to you

When I tried out the fake product, the first thing hit me straight away. The pin and socket were an extremely tight fit, requiring a hammer on my bench to achieve insertion. Then it proved extremely difficult to try and pull them apart. In short, if you made the cable connection (needing some mechanical vice to pull the halves together, then that's it for life. Anything else needs the coupling to be cut out and replaced. Are you happy with that?

IMHO no disconnecting joints should be made at all - ie make off the cables from the panels by cutting off the MC4 and replacing it with a continuous length of cable (with a properly crimped shroud butt joint). Thread the cable down to a ground level junction box and proceed thereafter as you wish (I prefer a crimped butt myself , always leave a loop of spare cable length for any future repairs).

Once inside your Solar shed - up to you - but at least you have ready visible inspection (Power Leccie's switchroom rule - Look Listen Smell).
 
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So panel to panel (same panel in the system) connections shouldn’t be an issue as they should be the same “style” MC4. Or do some of these cheaper panel manufacturers have a history of failures on factory supplied connectors?

It’s just the “home run” from the roof to the SCC/GT inverter that needs to be addressed/scrutinized.

I feel these cheap MC4 are just like those cheap failure prone “pop style” breakers that people gobble up only have headaches.
 
So panel to panel (same panel in the system) connections shouldn’t be an issue as they should be the same “style” MC4. Or do some of these cheaper panel manufacturers have a history of failures on factory supplied connectors?

It’s just the “home run” from the roof to the SCC/GT inverter that needs to be addressed/scrutinized.

I feel these cheap MC4 are just like those cheap failure prone “pop style” breakers that people gobble up only have headaches.
I don’t worry about cheap mc4 connections… or good ones either…screw em all…..after seeing how fragile and “iffy “ they are made( a dollar apiece Haa) .I cut all of them off every panel and crimp on high quality removable push on heat sealed with glue connectors rated at 45 amps …they are water proof and come apart with a simple pull… and then go back together with another push…

I use them for all electrical connections now for fast easy disconnects on the RV, car, mowers, all the solar panels , and pumps and stuff…
Yeah…yeah…
Not to beat a dead horse but I hate cheap shit…
 
I don’t worry about cheap mc4 connections… or good ones either…screw em all…..after seeing how fragile and “iffy “ they are made( a dollar apiece Haa) .I cut all of them off every panel and crimp on high quality removable push on heat sealed with glue connectors rated at 45 amps …they are water proof and come apart with a simple pull… and then go back together with another push…

I use them for all electrical connections now for fast easy disconnects on the RV, car, mowers, all the solar panels , and pumps and stuff…
Yeah…yeah…
Not to beat a dead horse but I hate cheap shit…
You got a linkor part number to the connectors you use??
 
I don’t worry about cheap mc4 connections… or good ones either…screw em all…..after seeing how fragile and “iffy “ they are made( a dollar apiece Haa) .I cut all of them off every panel and crimp on high quality removable push on heat sealed with glue connectors rated at 45 amps …they are water proof and come apart with a simple pull… and then go back together with another push…

I use them for all electrical connections now for fast easy disconnects on the RV, car, mowers, all the solar panels , and pumps and stuff…
Yeah…yeah…
Not to beat a dead horse but I hate cheap shit…
got a link to the connectors your using?
 
got a link to the connectors your using?
No link but here’s a pic… look it up on Amazon…l have several jars of the large ones and a mixed tray various size…

They have worked perfect since day one…
I heat seal the each wire on the two connector , push together but not heat seal the middle ..I wrap a short piece of waterproof tape over center part so it can be removed and pop the connection apart easily.
I like the 2 into 1 version to make a 3 wire union.
 

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No link but here’s a pic… look it up on Amazon…l have several jars of the large ones and a mixed tray various size…

They have worked perfect since day one…
I heat seal the each wire on the two connector , push together but not heat seal the middle ..I wrap a short piece of waterproof tape over center part so it can be removed and pop the connection apart easily.
I like the 2 into 1 version to make a 3 wire union.
Oh I hope this is a joke. Please don't tell me your using spade terminals.
 
No link but here’s a pic… look it up on Amazon…l have several jars of the large ones and a mixed tray various size…

They have worked perfect since day one…
I heat seal the each wire on the two connector , push together but not heat seal the middle ..I wrap a short piece of waterproof tape over center part so it can be removed and pop the connection apart easily.
I like the 2 into 1 version to make a 3 wire union.
Sorry but your explanation and your image of ring connectors does not seem to match. From your explanation I would expect some kind of socket and bayonet joint. Which is what MC4s are though they incorporate a lock and o-ring seal. Ring to ring, as your image would suggest, would need a bolt and nut for connect/disconnect.

Perhaps a photo of the connection you have would help.
 
FWIW in over 20 years of mixing MC4 connectors, I have only had one fail, and that was on the original panel connector going to an identical panel.
I've had many mc4's fail and melt. But then again I'm always mixing various mc4 connectors on various products. You never know what you're going to get
 
From array to scc pv input, I use non insulated butt splice connector sized properly, then cover the whole joint with marine grade heat shrink.

Please don't use spade connectors 😬
Well it’s a little hard to have confidence in a product when half of the name brand mc4 connectors I bought last year crumbled in my hand or twisted apart like stale crackers…
But then to each his own…

The only caution I would offer is use the correct crimp device , not an unspecified cheap one..

In my outdoor installation they work great that’s all I can say ….
 
Sorry but your explanation and your image of ring connectors does not seem to match. From your explanation I would expect some kind of socket and bayonet joint. Which is what MC4s are though they incorporate a lock and o-ring seal. Ring to ring, as your image would suggest, would need a bolt and nut for connect/disconnect.

Perhaps a photo of the connection you have would help.
It was the wrong picture but the correct company ..my internet has been off and on since yesterday and I couldn’t acquire the proper link..it’s been weak all morn....

you are correct as they are for the most part the post male/ female joint , but I do use the ring terminals on occasion for smaller wire..

Been using them for many years never the first problem .
 

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From array to scc pv input, I use non insulated butt splice connector sized properly, then cover the whole joint with marine grade heat shrink.

Please don't use spade connectors 😬
I have replace MC4s with butt connectors. A good quick fix, but not ideal for me since my arrays seem to get moved from time to time. I will just cut them off if I need to move anything.

Another option is if you don't have heat shrink or shrink terminals, you can squeeze some silicone inside the connector before inserting the wire. Rub some on the back sides to seal the ends. The crimp will still make great contact to the copper and voids get filled with silicone. They might actually last longer then heat shrink if you use a premium silicone. There are some cheap ones that can be slightly acidic.
 
It was the wrong picture but the correct company ..my internet has been off and on since yesterday and I couldn’t acquire the proper link..it’s been weak all morn....

you are correct as they are for the most part the post male/ female joint , but I do use the ring terminals on occasion for smaller wire..

Been using them for many years never the first problem .
I would not recommend them for high voltage. You can squeeze in some dielectric grease to help with voltage leakage and corrosion. It will run though if they get hot enough.

I had actually contemplated them at one point but I live in a very moist environment and even with grease, they would corrode. All my strings are low voltage and low power. Its not a good choice, but then again, I have used wire nuts on speaker wire for a small temp system once....
 
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I would not recommend them for high voltage. You can squeeze in some dielectric grease to help with voltage leakage and corrosion. It will run though if they get hot enough.

I had actually contemplated them at one point but I live in a very moist environment and even with grease, they would corrode. All my strings are low voltage and low power. It’s not a good choice, but then again,

Your thoughts are duly noted..thx… my full attention was used to address the issues you present…
All is cool with my system.

J.
 
I have replace MC4s with butt connectors. A good quick fix, but not ideal for me since my arrays seem to get moved from time to time. I will just cut them off if I need to move anything.

Another option is if you don't have heat shrink or shrink terminals, you can squeeze some silicone inside the connector before inserting the wire. Rub some on the back sides to seal the ends. The crimp will still make great contact to the copper and voids get filled with silicone. They might actually last longer then heat shrink if you use a premium silicone. There are some cheap ones that can be slightly acidic.
Use the silicon designed for electrical connections... I have a tube now and it has worked great ..

The standard stuff will corrode copper wire and part… just the off gassing will corrode copper if in tight quarters.
 
I would not recommend them for high voltage. You can squeeze in some dielectric grease to help with voltage leakage and corrosion. It will run though if they get hot enough.

I had actually contemplated them at one point but I live in a very moist environment and even with grease, they would corrode. All my strings are low voltage and low power. Its not a good choice, but then again, I have used wire nuts on speaker wire for a small temp system once....


See, I am thinking clean wires and a marine grade heat shrink with adhesive inside is the way to go. It is made for this sort of thing. And I don't mean the no-name stuff of amazon, like lugs, crimp tools, bus bars, and MC4 connectors there are many cheaper fakes that don't live up to their claim.



I've had many mc4's fail and melt. But then again I'm always mixing various mc4 connectors on various products. You never know what you're going to get

Life is like a box of MC4 connectors - you never know what you are gonna get. (said in my best Forest Gump accent)
 
I have done some crimped butt connectors, both with the heat shrink already on them, or non-insulated add your own heat shrink, and either way i am dubious about it because the 'jacketing' you're left with is much thinner and imo less UV-resistant than the insulation on 'factory' PV wiring. I consider it a weak spot when i make those connections, personally. Not that it wont hold up if left alone in darkness, but doesn't offer the same level of durability or protection as a 'functional' MC4 connection.

I have run into poorly-matching MC4s, but i blamed it on me buying the cheapest shit imaginable. I know paying more isn't a guarantee either but i didn't feel qualified to declare it a huge issue since i hadn't tried a bunch of brands at different price points. I consider it more of a cheap shit from China issue vs an MC4-specific thing.

Ive run into several melted MC4s in my setup. Mostly the cheap crap i bought. But one thing i always do is use dielectric grease because ive realized not only does dielectric grease keep away oxygen (thus oxidation), but it also works to thermally conduct heat away from the trouble spot more effectively than a 'dry' joint. Making little heat in a tiny spot with no way out = escalating temps until something melts. Making the same amount of heat but then dispersing it throughout the connection and nearby wiring = whole thing gets warm but nothing melts. It doesn't exactly fix a connection being bad from the start, but it does allow a connection to be worse without actually melting!
 
Use the silicon designed for electrical connections... I have a tube now and it has worked great ..

The standard stuff will corrode copper wire and part… just the off gassing will corrode copper if in tight quarters.
Thanks, good to know there is a specific silicone for copper!. I believe the clear cheap stuff is the worse.
 
It was the wrong picture but the correct company ..my internet has been off and on since yesterday and I couldn’t acquire the proper link..it’s been weak all morn....

you are correct as they are for the most part the post male/ female joint , but I do use the ring terminals on occasion for smaller wire..

Been using them for many years never the first problem .
Guys these are the standard "Lucas" pattern push fit connectors widely used in the auto industry for decades. However beware Chep Charlie, he makes these out of thinner metal so they dont maintain the spring force between blade and female socket.. Check your self to see the difference.
In principle these are very good but only go to 20A (6.3mm blade). However there is a 9.5mm blade version (yellow) but you can only get it in FEMALE. The industry only expected these to be used on equipment ie connecting a dynamo. Good for 40A maybe. I have a collection of these Ebay). Sorry not allow to mention here. I use the uninsulated crimp pair versions together with crimp/solder (at core tip - dont let it wick down the cable) then apply glue heatshrink. a silicon tube shroud can be fitted over the coupling with si grease. Pulls apart easily for occasional maintainance. Its old school and you can inspect it - unlike rubbish MC4s

But thats my 10c YMMV
 
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